Atomistic simulation of the mechanical response of a nanoporous body-centered cubic metal

Scaling laws and deformation mechanisms of nanoporous copper under adiabatic uniaxial strain compression

“…At the elastic stage, the porosity decreases with a smaller slope with increasing strain. However, the porosity suffers a steeper decrease at the plastic stage with dislocation-mediated void collapse due to the densification under adiabatic uniaxial compression, 37 which will be shown in detail shortly. Voids collapse completely and the porosity disappears at a critical strain (10% for 97.6% relative density, 12% for 95.2% relative density, 16% for 90.5% relative density, and 25% for 81% relative density), and at this point the strain hardening effect become noticeable in the stress-strain curves as shown in Fig.…”

“…The samples were then subjected to uniaxial compressive strain along X direction, with zero lateral strain. 37 The simulations were conducted at a strain rate of 5×10 8 s -1 (600 ps, 30% volumetric strain). In order to capture thermal effects related to adiabatic uniaxial strain compression, no temperature control was used during loading.…”

“…[25][26][27][28] Previous MD simulations have been conducted to investigate the collapse of a single nanovoid or a collection of nanovoids in both fcc and bcc metals at high strain rates. 27,[29][30][31][32][33][34][35][36][37][38][39] These studies have focused on dislocation activities and the resulting porosity evolution in nanoporous metals. Under high rate loading, the void surfaces were found to be dislocation sources, and their collective interaction leading to very high dislocation densities.…”

“…Under high rate loading, the void surfaces were found to be dislocation sources, and their collective interaction leading to very high dislocation densities. 31,37 Moreover, the loading orientation and stress states were found to have strong effects on the sequence in which the loops form and interact. 34 With increasing strengths, void collapse was observed to transit from the "geometrical" mode to "hydrodynamic" mode in Cu nanofoam with high initial porosity of 50%.…”

“…27 Interacting of multiple voids was also found to decrease the stress required for the onset of plasticity under adiabatic uniaxial compression, compared to that for isolated void. [34][35][36][37]39 However, the scaling laws and the underlying atomistic mechanisms of nanoporous metals under adiabatic uniaxial strain compression are still open to further investigations. In this regards, the focus of this paper is to understand the effects of the relative density and the void diameter on the adiabatic uniaxial compression behaviors and the related atomic-level deformation mechanisms in nanoporous copper using MD simulations.…”